Barack Obama has managed to ride out his first five months in office by blaming his predecessor for the economic tribulations he “inherited”, but new polling shows that excuse running out of steam.  Although a majority still give George Bush more blame than Obama, those numbers have fallen quickly as Obama’s stimulus spending fails to stop runaway unemployment, according to Rasmussen:

While most U.S. voters still blame the Bush Administration for the nation’s economic problems, a growing number are inclined to blame President Barack Obama.

A new Rasmussen Reports national telephone survey finds that 39% of voters now say the country’s economic problems are caused more by the policies Obama has put in place. That’s a 12-point jump from a month ago.

Fifty-four percent (54%) still say the country’s economic woes are due to the recession Obama inherited from President Bush. That figure is down eight points from 62% from early June.

That’s a 20-point shift, a significant movement in just two weeks.  The biggest factor may be the unemployment report in early June that showed joblessness rising much faster than Obama’s team had predicted, even without a $787 billion stimulus bill.  If so, then we can expect a major shift when unemployment crosses the double-digit threshold, as even Obama predicts it will this year.  We can call that the expiration date for blaming Bush, and the moment when the economy becomes Obama’s fault, as his expensive and expansive policies fail to arrest the economic decline.

The crosstabs, as always, show some interesting motion.  Majorities of both whites and blacks blame Bush, but a majority of “Others” (primarily Asians and Hispanics) blame Obama, 54%-43%.  Independents split on the question, 48%-46%, leaning towards blaming Obama, a big problem if that moves towards a majority. Democrats and Republicans have predictable splits, as do conservatives and liberals, but the most interesting split comes in the Political Class demographics.  Without leaners, a plurality of self-described “mainstream” people blame Obama, while 100% of the self-professed political class blame Bush.

Nor does it look good for the future of Obama’s economic policy.  This question had less to do with the current crisis and more to do with Obama’s policies for reversing it.  A large majority believes they know better than Obama about economic issues, 60%-30%.  That holds true in almost every demographic category, with a few notable exceptions.  Blacks trust Obama more than themselves, 72%-21%, and liberals by 54%-30%, but Democrats can’t even get a majority for that position, 48%-37%.  Independents trust themselves more than Obama by a whopping 76%-19%, almost identical to Republicans.  A majority of higher-income workers (between $60-100K) blame Obama; the under-$20K demographic, which one could expect to be loyal to Obama, trust themselves more than Obama’s economic leadership, 49%-39%.

Obama only has a few weeks at most to keep using the “inherited from my predecessor” defense, if that.  The next joblessness report comes out in early July, and it will probably spell an end to that defense, as well as support for Obamanomics in general.

Update (AP): If it’s not Obama’s economy yet, it will be soon.